The need to calibrate

On bars these days you find more and more usage of scales and thermometers but less and less interest in calibration. Like most things, there is a balance between dependence on something and willingness to check that what we depend on is accurate.

Here are a few things to calibrate and a few easy ways to calibrate them.

Scales: Some scales come with a gram weight which can be used for calibration. Alternatively, you can purchase a set of weights for calibration purposes. For your small scale that would be measuring amounts such as gram doses, a nickel is a good calibration tool. A nickel weighs 5g and once you have zeroed and tared your scale, you can simply place a nickel on it to see if it is accurate. A better way of calibrating a scale though is to measure the maximum capacity of the scale. If the scale maxes out at 5lb, finding something like a 5lb bag of sugar to measure the maximum of the scale. RTFM applies in all situations as many models of scales have calibration modes outlined in the manual.

It is also a good idea to make sure the scale you use for measuring small gram dose weights has a small enough resolution to be practical. Some scales have resolutions that vary as much as 5g as they are designed for weighing larger amounts, some are used for precision measurements of small amounts but need to be tared often or reset and tared between measurements.

Thermometers: Thermometers are easy to calibrate and hopefully everyone manual brewing coffee is measuring temperature. To calibrate a thermometer, simply fill a cup with mostly ice and a little bit of water allowing more than 80% of the probe to be submerged. Let the thermometer sit submerged for one minute and then observe the temperature. It should measure at 32f/0C. In conjunction, a measure of water at a rolling boil can give another data point. Placing the same probe into water at a rolling boil should give you a measuring point of 212f/100C unless you are at high elevation to which your boiling point may differ. (To verify espresso temperatures, we recommend getting a Scace and calibrating it the same way in both ice water and boiling to establish group head temperatures.)

Note: The usefulness of calibrating thermometers was most apparent for us. With our installation of two roasters (identical), we found the temperature probes (and spares) had a range of variance within 2 degrees. After identifying the offsets, we then programmed this into the displayed temperatures. When changing the temp probes, we would have to repeat the process of calibration.

Flow Meters: The traditional flow meter in an espresso machine is one of the most difficult items a professional barista can use. In many cases, we tend to abandon this because constant recalibration is needed. The reason being that in the dual boiler machines we use, the volumetric component isn't designed for precision and is placed in a position where hot water sits and scale buildup occurs. This creates many problems that makes it less than useful and often a hinderance. Recalibrating involves either a scale weight of the resulting shot (remember mL and grams are exchangeable) or a volumetric estimate with a 'shot glass.'

In the next year, a new type of flow meter will be introduced in coffee brewing that should not be confused with the volumetric controls on an espresso machine. The LuminaireCoffee volumetric controls are a generation ahead in that they function with more accuracy and are more useful in what they display. As opposed to the volumetric controls on an espresso machine, the LuminaireCoffee flow meter is in the cold water section and has less issues with buildup or hard water. It also is precision and digital which is best exemplified when using it in manual mode as it functions similar to a chronos display of time on a La Marzocco espresso machine. It simply displays total cumulative volume and time counts (and a dynamic flow in either ml/s or oz/min) as you are brewing. (In preset mode, it has cutoffs that can be set to stop the flow at either time or volume points.) Calibration of this is done at production but can also be done by measuring a specific volume of water in a specific time count with a calibrated scale. It makes brewing onto a scale to measure volume a bit superfluous (once calibration is verified). See Flow and Profiling posts for more relevant discussion.

Pressure profiling, flow rate profiling, and the future of temperature profiling

We admit being hesitant to get involved with pressure profiling. Simply put, there were too many problems we had to deal with in accounts to add one more major variable.

Our opinions were refined and changed by first working with Ben and Cora at RBC during a guest stint where we got a few coffees really dialed in using pressure profiling. It was an experience that has continued to get us good feedback on how the coffees come out when the pressure is tweaked. This was further cemented by experiences at Worldbean.

If pressure profiling is the future for a certain market segment, we have to wrap our heads around this a little more and see how it develops. What it points to for us is how the technology in our industry is about to get much more tech very quickly. Keeping up with what is happening and discerning which advances are quality may take some time.

When Clover launched, we were one of the critics of the brewer. The silty metal filtration, the heat wrap issues, and the new brew method it created. We always noted however they were really cool people working there but from a coffee standpoint, we didn't like it. Our opposition to the clover though left us out in the cold in a lot of community discussions because it was what had been trending and everyone was rushing to adopt it so they likewise flamed anyone who disagreed. It took nearly a hundred units being out there before a larger voice of opposition formed and the sale to Starbucks cemented it for many. Now, there are plenty of people against it and still more looking for a new design that doesn't reinvent how we brew coffee, only aids making it.

I am wondering this aloud because as the Lb-1 launches soon, I realize it will take time to seep in exactly the implications of this technology and how it will change how we brew. Sure, we've had versions of this over the last two years and fully get where it's coming from, but there will be many naysayers and many would be early adopters to take that leap.

The fact though is, Luminairecoffee technology will open the door to flow profiling with precision temps. The ability to control and tune flow rate throughout a brew in pour over methods. The following higher capacity version will offer an ability to bulk brew. There's also a top secret project that may show up in a top secret shop opening soon in Cambridge that will be a potential vision of where espresso may go if some of this technology were converted. The current version of the Lb-1 has temperature controls that are unheard of. While the forumphiles and keyboard warriors talk about their different metrics for measuring extraction, we've been lucky to be geeking on something that has precision, repeatable volume/temperature controls making measuring results less useful that observing the inputs. We can even stop and adjust temps mid brew where the pause is only how long it takes to hit a small button sequence. At some point, temperature profiling will be a very real addition, though the requirements to implement it would require much more user interface and would slow production considerably.

So, it could be said, I've had a glimpse of the future. The real revelation is what comes next. These first generation versions of Luminairecoffee technology that will be far surpassing anything else on the market will be the first of a new control that goes beyond previous inventions. While the old engineering maxim of 'fast, cheap, and quality pick two of three' usually applies, this is the exception. Using technology that is cheaper to make and costs less to run (high energy efficiency=cheap), has a zero refresh time (so fast!), and actually produces more consistent and precise temperatures than existing PID'd small boiler technologies(quality).

So some people were commenting how it looks good on paper and how they were skeptical or how it compares it to the boilers out there. I'll file that with the list of things where people have been against something we were exploring, championing, or working with just before it became big in the larger community. Be it as early adopters of specific brew methods, championing progressive packaging, challenging transparency in blends, or the other things we have had detractors line up against, you develop a very thick skin after a while. It all seems to eventually make it main stream or at least catches on enough in small segments that we no longer hesitate to move to back what we believe in.

If US coffee is facing a renaissance of sorts then pressure profiling, flow controls, and temperature profiling are the inevitable. How we get there will either take a long time or be on the backs of small bits of genius that change our entire industry. Here's hoping we are seeing the latter.